EARTHQUAKE RESISTANCE STRUCTURE

RESILIENT STRUCTURAL SYSTEMS

1. GURUVIGNESH N 1
RESILIENT STRUCTURAL SYSTEMS
(EARTHQUAKE RESISTANCE)
Submitted by
GURUVIGNESH N
Reg. No :910018413004
M.E.-STRUCTURAL ENGINEERING (FULL TIME)
ANNAUNIVERSITY REGIONAL CAMPUS
MADURAI

2. INTRODUCTION
Includingmechanicaldevicesin
structuralsystemscanleadto
enhancementofperformanceof
structurestoextremeloadings
thesedevicescanbedesignedto
providerequiredstrengthwhile
controllingbehaviortoprotect
structuralelementsfromdamage
systemcanbedesignedtofuse
duringsuchextremeeventsasstrong
earthquakegroundmotion
GURUVIGNESH N 2

3. EARTHQUAKES WORK
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One of the most terrifying phenomena
Until recently -unsubstantiated guesses as to what
caused earthquakes
Today –much clearer understanding
Identified forces of earthquakes
Technology that can tell an earthquake’s
magnitude
Technology that can tell an origin
OBJECTIVES
To find a way of predicting earthquakes
To find way to protect people and property

4. THEORY OF PLATE TECTONICS
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Thesurfacelayerofthe
earththelithosphere
slideoveranother
layer
threedifferentthings
oPlatesslideagainst
eachother
oPlatescanmoveapart
oPlates can push
together

5. SEISMIC WAVES
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suddenbreakorshiftoccursintheearth'scrust,-
theenergyradiatesoutasseismicwaves
Ineveryearthquake,thereareseveraldifferent
typesofseismicwaves
Bodywavesmovethroughtheinnerpartoftheearth
Surfacewavestraveloverthesurfaceoftheearth.
Surfacewaves--sometimescalledlongwaves,or
simplyLwaves--areresponsibleformostofthe
damageassociatedwithearthquakes,becausethey
causethemostintensevibrations.Surfacewaves
stemfrombodywavesthatreachthesurface.

6. CAUSES OF EARTHQUAKE
An earthquake is a vibration that
travels through the earth's crust.
Natural causes
oVolcanic eruption
oWater pressure in reservoir
oMeteor impacts,Rock fall
oMovements of the earth’s
plates
Man made causes
oCollapsing structures
oUnder ground explosions
GURUVIGNESH N 6
THEORIES
1.ELASTIC
REBOUND
THEORY
2.TECTONIC
PLATETHEORY

7. Surface wave:
The slowest traveling seismic
waves
Their movement is greatest at
the earth's surface, and gets
smaller
P-wave
A longitudinal wave
Travelrock, liquid and the air
The fastest traveling seismic
wave
S-wave
A transverse wave
Travel rock, but not through
liquid and the air
slower than a P-wave, but
faster than a surface wave
7GURUVIGNESH N
SEISMIC WAVES

8. BUILDING HEIGHT TYPICAL NATURAL PERIOD
2 story .2 seconds
5 story .5 seconds
10 story 1.0 seconds
20 story 2.0 seconds
30 story 3.0 seconds
BUILDING HEIGHTS & NATURAL
FREQUENCY
Natural period = no of stories * 0.1

9. Buildingsaredesignedtowithstand
verticalforces.Ifearthquakesonly
movedthegroundvertically,buildings
mightsufferlittledamagebecauseall
structuresaredesignedtowithstand
verticalforcesassociatedwithgravity
Buttherollingwavesofan
earthquakeexertextremehorizontal
forcesonstandingstructures.
These forces cause lateral
accelerations.
GURUVIGNESH N 9
FORCES

10. SEISMIC
ZONE
II III IV V
Seismic
intensity
Low Moderate Severe Very
severe
Z 0.10 0.16 0.24 0.36
SEISMIC
ZONE LEVEL
REMARK
III,IVand VDepthb/w 5
to 10 m
II(for
important
structure
only)
Depthb/w 5
to 10 m
10GURUVIGNESH N

11. SEISMOLOGY
Theydothiswithaseismograph,
amachinethatregistersthe
differentwaves
Tofindthedistancebetweenthe
seismographandthefocus,
scientistsalsoneedtoknowthe
timethevibrationsarrived
Withthisinformation,they
simplynotehowmuchtimepassed
betweenthearrivalofboth
wavesandthencheckaspecial
chartthattellsthemthe
distancethewavesmusthave
traveledbasedonthatdelay.
GURUVIGNESH N 11

12. These two ratings describe the power of the
earthquake from two different perspectives.
oThe Richter Scale is used to rate the
magnitudeof an earthquake --the amount of
energy it released
oThis is calculated using information gathered
by a seismograph.
Mercalliratings only give you a rough idea of
the actual impact of an earthquake
MAGNITUDE –NUMBER-ENERGY RELATED
INTENSITY -NOTATION –DAMAGE RATE
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RICHTER SCALE RATING AND
MERCALLI SCALE RATING

13. EARTHQUAKE RESISTANT
BUILDINGS
Earthquakescancausebuildingstovibrate
Everybuildinghasanumberofways,or
modes,inwhichitcanvibratenaturally.In
eachmode,thebuildingvibratestoa
particulardistortedshapecalleditsmode
shape.
Earthquakesusuallymakebuildingsvibrate
moststronglyintheirfundamentalmode,the
modeofvibrationwiththelowestfrequency
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14. STRENGTHENING BUILDINGS
FOR EARTHQUAKES
Earthquakes cause sideways forces on
buildings
These are some of the structural
systems used to resist sideways forces
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1.HORIZONTAL
STRUCTURAL SYSTEM
2.VERTICAL STRUCTURAL
SYSTEM

15. HORIZONTAL STRUCTURAL
SYSTEMS
Usuallyfloorsandroofs
Theysharethesidewaysforceson
thebuildingbetweenitsvertical
structuralmembers.
They include:
Diaphragms
Trussing
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16. HORIZONTAL DIAPHRAGMS
Horizontaldiaphragmsare
usuallyfloorsandroofs.They
aremadeupfromahorizontal
framecoveredbyafloororroof
deck.
Whenadiaphragmisstiff
enoughinitshorizontalplane,it
cansharethesideways
earthquakeforcesonabuilding
betweentheverticalstructural
members,e.g.thecolumnsand
walls.
GURUVIGNESH N 16

17. HORIZONTAL TRUSSING
Horizontaltrussingis
usuallyusedinroofswhere
thereisnotenoughdeckto
allowtherooftoactasa
stiffhorizontaldiaphragm.
Thetrussingtransfersthe
sidewaysearthquakeforces
onabuildingtoitsvertical
structuralmemberse.g.the
columnsandwalls.
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18. VERTICAL STRUCTURAL
SYSTEMS
Made up from columns,
beams, walls and bracing.
They transfer the sideways
forces on the building to
the ground.
They include:
Braced frames
Moment resisting frames
Shear walls
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19. GURUVIGNESH N 19
Braced frames use trussing to resist sideways forces
on buildings.
Trussing, or triangulation, is formed by inserting
diagonal structural members into rectangular areas of
a structural frame.
It helps stabilisethe frame against sideways forces
from earthquakes and strong winds.
BRACED FRAMES
Single diagonals
Cross-bracing
Other ways of bracing frames

20. OTHER WAYS OF BRACING
FRAMES
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Knee Bracing
V Bracing
K Bracing
Knee Bracing

21. MOMENT RESISTING FRAMES
Inmomentresistingframes,
thejoints,orconnections,
betweencolumnsandbeams
aredesignedtoberigid
Thiscausesthecolumnsand
beams tobendduring
earthquakes.So these
structuralmembers are
designedtobestrongin
bending.
Momentresistingframes
simplymeansframesthat
resistforcesbybending.
GURUVIGNESH N 21

22. SHEAR WALLS
Shearwallsareverticalwalls
thatareusedtostiffenthe
structuralframesofbuildings.
Theyhelpframesresist
sidewaysearthquakeforces
Theearthquakeforcesare
transferredtotheground
mainlybyshearforcesinthe
walls
Itisbettertousewallswith
noopeningsinthem.
Usuallythewallsaroundlift
shaftsandstairwellsareused
Wallsonthesidesof
buildingsthathavenowindows
canbeused. GURUVIGNESH N 22

23. Techniques to be Adopt on
Skyscrapers
Base isolation
Rubber bearings
Friction dampers
Metallic dampers
Friction pendulum
Viscous dampers
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24. baseisolation--involvesfloatingabuilding
aboveitsfoundationonasystemof
bearings,springsorpaddedcylinders.
24GURUVIGNESH N
BASE ISOLATION

25. BASE ISOLATION
25GURUVIGNESH N

26. RUBBER BEARINGS
Rubberbearingsaremadefromlayersofrubber
withthinsteelplatesbetweenthem,andathicksteel
plateonthetopandbottom.
Thebearingsareplacedbetweenthebottomofa
buildinganditsfoundation.
Thebearingsaredesignedtobeverystiffand
strongforverticalload,sothattheycancarrythe
weightofthebuilding.However,theyaredesignedto
bemuchweakerforhorizontalloads,sothattheycan
movesidewaysduringanearthquake.
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27. Rubber attached at foundation
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28. METALLIC DAMPERS
Metallic dampers are usually made from steel.
They are designed to deform so much when the
building vibrates during an earthquake that they cannot
return to their original shape.
This permanent deformation is called inelastic
deformation, and it uses some of the earthquake energy
which goes into building.
GURUVIGNESH N 28
X -Plate Metallic Damper

29. FRICTION DAMPERS
Friction dampers are designed to
have moving parts that will slide
over each other during a strong
earthquake.
When the parts slide over each
other, they create friction which
uses some of the energy from the
earthquake that goes into the
building.
GURUVIGNESH N 29

30. FRICTION PENDULUM BEARINGS
Frictionpendulumbearingsare
madefromtwohorizontalsteel
platesthatcanslideovereach
otherbecauseoftheirshapeand
anadditionalarticulatedslider.
Theyaredesignedtobevery
stiffandstrongforverticalload,
sothattheycancarrytheweight
ofthebuilding.
GURUVIGNESH N 30

31. VISCOUS FLUID DAMPERS
Viscous fluid dampers are similar to shock absorbers
in a car. They consist of a closed cylinder containing a
viscous fluid like oil.
A piston rod is connected to a piston head with small
holes in it. The piston can move in and out of the
cylinder. As it does this, the oil is forced to flow
through holes in the piston head causing friction.
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32. San Francisco Airport International Terminal
World’s Largest Isolated Building

35. GURUVIGNESH N 35
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